'The Act (and Art) of the Doc' moderated by Scott Roxborough, The Hollywood Reporter's Cologne-based correspondent, revealed the difficulties that even producers of the stature of Andre Singer, who worked on Oscar-nominated The Act of Killing, and German director Marc Bauder (Master of the Universe), face when financing their films.

Most documentary films get made through "the sheer bloody-mindedness of the director," Singer noted.

Singer is in Berlin to present his new project, which he is also directing, Night Will Fall, a work in progress about the liberation of Nazi death camps by Allied soldiers in 1945 that features interviews with troops and camp survivors seen in wartime footage, now in their 80s and 90s.

The Act of Killing director Joshua Oppenheimer spent eight years working on the film and put the funding together "piecemeal," he added.

"It was only when the funders saw the material they understood that as a filmmaker he had something special to offer that was really different," Singer said.

Bauder, whose candid study of a highly placed financial executive -- the sort of person the public identify as being responsible for the global finance crisis -- focused on one man's compulsion to tell his story, took a very different path.

"The more bizarre and apparently unsalable the film is, the better; audiences want something different," she said. Fantastic content and fresh formats always sold, despite the general retreat from documentary funding by many television broadcasters, she added.

Documentary films, even of those such as Oscar-winning Searching For Sugarman -- which took around $3 million worldwide -- were not big money spinners, Singer said.

But the panel agreed that P&A budgets helped raise the profile of a movie and although crowd-funding and other social media tools could help identify audiences, traditional funding routes -- through TV, public funding bodies and film commissions -- remained the most viable route to success.